diff --git a/classes/frontend.php b/classes/frontend.php
index 2791a1d..f9c18eb 100644
--- a/classes/frontend.php
+++ b/classes/frontend.php
@@ -34,8 +34,8 @@ protected function get_javascript_strings(): array {
         return ['label_state', 'label_question', 'ajaxerror'];
     }
 
-    protected function get_javascript_init_params($course, \cm_info $cm = null,
-            \section_info $section = null): array {
+    protected function get_javascript_init_params($course, ?\cm_info $cm = null,
+            ?\section_info $section = null): array {
 
         // Get all quizzes for course.
         $quizzes = $this->get_all_quizzes($course->id);
@@ -74,8 +74,8 @@ protected function get_all_quizzes(int $courseid): array {
         return $this->allquizzes;
     }
 
-    protected function allow_add($course, \cm_info $cm = null,
-            \section_info $section = null): bool {
+    protected function allow_add($course, ?\cm_info $cm = null,
+            ?\section_info $section = null): bool {
 
         // Only show this option if there are some quizzes in the course.
         return !empty($this->get_all_quizzes($course->id));